Current control circuit arrangement



Jan. 2 6, 1965 w MAAG CURRENT coNTRoL CIRCUIT ARRANGEMENT Filed sept. e, 1960 United States Patent O 3,167,704 CURRENT CNTRL CKRCUIT Walter Maag, Geroldswil, Switzerland, assigner to E. A. Schlatter Alrtiengesellschai't, Zollitron, Zurich, Switzerland Filed Sept. 8, 196?, Ser. No. 515,714 Claims priority, application Switzerland, Sept. 9, 1959, 73,969 6 Claims. (ill. 321-53) The present invention relates to a circuit arrangement for controlling current. More particularly, the invention relates to a circuit arrangement for controlling current in a power or power supply circuit converting three-phase AC. to a single-phase A.C., which circuit arrangement is particularly suitable for welding apparatus.

ln the circuit arrangement of the present invention, two rectifier or phase converting circuits are provided for alternate rectification or phase conversion of each phase of the polyphase current, and the operation of said rectier or phase converting circuits is controlled by a control circuit in accordance with the phase or half cycle polarity of the single-phase current.

An object of the present invention is to provide a circuit arrangement for preventing overcurrents in a power circuit. Such overcurrents occur, when the power circuit is enerized, due to the remanence or residual magnetism of the core ci a transformer connected in the single-phase circuit. The transformer may comprise, for example, the transformer of welding apparatus. As is known, the overcurrents prevented by the circuit arrangement of the present invention develop when the power circuit is energized at a time when the momentary magnitude of voltage corresponds to an induction change or magnetization which is approximately equal to the residual induction or residual or remanent magnetization from the next preceding energization of said power circuit. In such an instance, the induction or magnetization of the core of the transformer at the moment of energization of the power circuit is changed only slightly, no self-induced voltage develops, so that the current at the moment of energization is determined essentially solely by the ohmic resistance of the circuit and greatly exceeds the magnitude necessary for the actual operation.

1t is known that the generation of such overcurrents may be prevented by energizing the transformer during a half cycle of opposite polarity from the polarity of the 'ralf cycle at which the transformer was deenergized. However, this necessitates that the interval between the deenergization and energization correspond to an even number of half cycles.

rthe present invention permits the interrupting of the single-phase current obtained from a polypnase current at intervals of any desired length and still prevents the generation of overcurrents at the time of energization of the power supply circuit.

1n the circuit arrangement of the present invention, the control circuit comprises a ring counter circuit with an even number of stages each of which is controlled by a time delay circuit. One of the two diametrically opposed stages of the ring counter circuit releases the ignition signals for the rectifier circuit for one half cycle (one polarity) of the single-phase current, and the other of the diametrically opposed stages releases the ignition signals for the rectiier circuit for the other halt cycle ICC (the opposite polarity) of the single-phase current. Each of the stages of the ring counter circuit is connected by switching means to a control signal supply line of a control signal source and each of said stages may be set in operation by a signal which serves to switch on the single-phase current. The switching means conductively connects, under the influence of each half cycle of the single-phase current, the control signal supply line with a control element of that one of the two stages of the ring counter circuit which releases the ignition signals for the rectitier circuit of the opposite half cycle.

ln accordance with one embodiment of the circuit arrangement of the present invention, the aforementioned switching means comprises a polarized relay which is energized by the single-phase current and which is provided with a make-break contact. The make-break contact connects the control signal supply line during each half cycle of thc single-phase current with that one of the two stages of the ring counter circuit which releases the ignition signals for the rectiier circuit or" the opposite half cycle of the single-phase current.

in accordance with another embodiment of the circuit arrangement of the present invention, each of the two diametrically opposed stages of the rin@ counter circuit is connected by a gate circuit to the control signal supply line. A bistable device, which depends on the polarity of the half cycles of the single-phase current, opens, under the influence or" each half cycle of the single-phase current, that gate circuit which is provided between the control signal supply line and that stage of the ring counter circuit which releases the ignition signals for the rectifier circuit for the half cycle of opposite polarity. The bistable device may comprise, for example, a bistable multivibrator or lip-op circuit.

The aforementioned switching means are preferably connected with the circuit of the single-phase current by means which does not transmit self-induced voltages developing in the single-phase circuit during the energization of the power supply circuit. The aforementioned means may comprise an integrator circuit.

1n order that the present invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, wherein:

FIG. l is a schematic diagram of an embodiment of the current control circuit arrangement of the present invention; and

FlG. 2 is a schematic diagram of another embodiment of a portion of the circuit arrangement of PEG. l.

In FlG. l, the three conductors of a three-phase input network of a power supply circuit are indicated by R, S and T, respectively. The conductor R is coupled to one end of primary winding 21 of a transformer 2 through two ignitrons 1i and 1d which are connected in antiparallel arrangement. The transformer 2 may comprise, for example, a welding transformer for supplying cur- 'ent from the power supply circuit to welding apparatus. The conductor S is coupled to said one end of the primary winding 21 through ignitrons 12 and 1S which are conected in antiparallel arrangement. The conductor T is coupled to said one end of the primary winding 21 through two ignitrons 13 and 14 which are connected in antiparallel arrangement. As shown, the said one end of the primary winding 21 of the transformer 2 is connected to the cathodes 112, 122 and 132 of the ignitrons 11, 12 and 13, respectively, and to the anodes 141, 151

and 161 of the ignitrons 14, 15 and 1-5, respectively. rthe ignitrons 11, 12 and 13 comprise a rectitier or phase converting circuit for converting the three-phase AC. to single-phase AC. during the positive half cycle of the single-phase A.C. and the ignitrons 14, 15 and 1o comprise rectifier or phase converting circuit for converting the three-phase A.C. to single-phase A.C. during the negative half cycle. The other endV of the Winding 21 of the transformer 2 is connected to the neutral point O of the threephase network. The transformer 2 has a core 2l) and a secondary Winding 22 which may feed, for example, a welding circuit or Welding apparatus 23. Anode 111 of the ignitrons 11 is connected to anode 311 of a thyratron 31, and ignition electrode 113 of the ignitron 11 is connected to cathode 312 of the thyratron 31. Secondary Winding 313 of a transformer 31dis connected in the grid circuit of the thyratron 51 in series with a source 315 of grid bias voltage. One terminal of primary Winding 31d of the transformer 314 is connected to anode 411 of a cold-cathode tube 21. The other terminal of the primary Winding 316 ofthe transformer 314 receives a square wave voltage which is in phase with the anode voltage of the thyratron 31 and with the anode voltage ot the ignitron 11. T he square Wave voltage applied to the other terminal of the voltage primary Winding 315 of the transformer 314i is provided by a source of square wave voltage S14, which source may comprise any suitable square Wave generating means.

rEhe ignitrons 12, 15, 1d, 15 and 15 are connected to thyratrons 32, 33, 34, 35 and .'55, respectively, each such connection including a transformer and a source of grid bias voltage, as Well as a cold cathode tube 42, 45, 413, and 46, respectively, and a source of square Wave voltage S24, 834, S4111-, S54 and 864, respectively, which is in phase with the anode voltage of the respective thyratron and ignitron, in the same manner in which the ignitron 11 is connected to the thyratron 31 and in the same manner of connection as the transformer 314 and the source ol` grid bias voltage 315, as Well as the cold cathode tube 41 and the square Wave voltage source S14.

ignition electrode 41T of the cold cathode tube 41 is connected through a capacitor 414 to a pulse source 415. r:The pulse source l115 may comprise any suitable pulse generating means which produces pulses in an adjustable phase position with respect to the single-phase current. The pulses produced by the pulse source 415 and applied to the capacitor 414i aid in controlling the production of the single-phase current by the power supply circuit. ln analogous manner, the ignition electrodes of the cold cathode tubes 42, 43, d4, l5 and lo receive pulses from pulse sources 125, 43S, 445, 455 and 465, respectively. However, each of the tubes d1, ft2, 43, if-3, 45 and e will ignite only if, in addition to the aforementioned pulses, there is a positive bias or preliminary voltage on the respective ignitron electrodes 113, 423, 453, 4145, 453 and 4163. The bias or preliminary voltage is produced in a manner described hereinafter and is respectively applied to said ignition electrodes through resistances 41e, 42e, 4:36, 445, 455 and der?.

The phase converting control which controls the ignitrons 11, 12, 13, 14, 15 and 16 in accordance with the frequency pt the single-phase current comprises a ring counter circuit 5. The ring counter circuit 5 contains four cold cathode tubes 51, 52, 53 and 5ft, each of which is connected to a source of positive potential through a common resistance 5d. The cathode of each of the cold cathode tubes 51, 52, 53 and 54 is connected to a source of negative potential, such as, for example, a point at ground potential, through a resistance which is shunted by a capacitor. Thus, for example, cathode 512 of the cold cathode tube 51 is connected to the source of negative potential through a resistance 515 which is shunted by a capacitor 516. rl`he cathode 512 of the tube 51 is connected to ignition electrode 523 of the tube 52 through a tilde delay circuit 517. Cathode 522 of the tube 52 is connected to ignition electrode 533 of the tube 53 through a time delay circuit 527. Cathode 532 ot the tube 53 is connected to ignition electrode 545 of the tube 541 through a time delay circuit 537. ln addition, cathode 5e?, of the tube 54- is connected to ignition electrode 513 of the tube 51 throuvh a time delay circuit 547. in this manner, the tubes 51, 52, 53 and 54 form a ring counter circuit. The time delay circuits 517, 527, 537' and 547 each comprise any suitable time delay means, such as, for example, an RC circuit.

in FIG. l, the tubes 51, 52, 53 and 54 are not shown in an annular arrangement in order to maintain the clarity of the drawing. if the tubes 51, 52, 53 and 54 were to be shown in an annular arrangement, the tubes 51 and 53 and the tubes 52 and 54 would be disposed diametrica..y opposite each other. rEhe cathode 512 of the tube el is connected through a gate circuit 61 and through the respective resistances 516, 425 and 435 With the ignition electrodes 413, 423 and 433 of the tubes 41, 42 and 43, respectivey. The gate e1 may comprise, for example, a resistance 611 connected in series in the line between the input and output of said gate and a diode 612 connected in parallel With said line. in an analogous manner, the cathode 532 of the tube 53, which in an annular arrangement of the ring counter circuit 5 Would be disposed opposite the tube 51, is connected t1 rough a gate e2 and through the respective resistances 445, 456 and 166 With the ignition electrodes 443, 55 and 453 of the tubes 44, 5 and 4o, respectively. The gate 62 may comprise, for example, a resistance 621 connected in series in the line betrl een the input and output of said gate and a diode connected in parallel with said line. Since the tubes 41, 42 and 43 are associated with the ignitrons 11, 12 and 13, respectively, Whose cathodes 112, 122 and 132, respectively, are in turn connected with the primary Winding 21 of the transformer 2, While the tubes 4d, 45 and l5 are associated With the ignitrons 14, 15 and 16, respectively, whose anodes 141, 151 and 161, respectively, are connected with the primary Winding 21 of the transformer V2, one half cycle of the single-phase current in the transformer 2 corresponds to each one of the diametrically opposed stages of the ring counter circuit 5 and the other ralf cycle ot the single-phase current in the transformer 2 corresponds to the other of the diametrically opposed stages of the ring counter circuit 5.

Each of the two tubes 51 and 53 includes a second ignition electrode 514i and 534i, respectively, which is connected to a rst control signal supply line 81 of control signal source S through a respective ampliiier '713 and and a respective gate circuit 71 and 72. The control signal source S provides in the control signal supply line 51 a positive control signal or pulse 811 for each energizetion of the power supply circuit; that is, each time the transformer 2 is energized by the single-phase current.

Each of the gates 71 and '72 comprises a diode 711 and 721, respectively, and a resistance 712 and 722, respectively, and each of sai gates is controlled by one ot the two stages ot a bistable multivibrator 9. The multivibrator 9 preferably comprises a dip-flop circuit of known design which is only partially shown in the drawing of FlG. l and which may comprise, for example, two cold cathode tubes 91 and whose anodes 911 and 921, respectively, are connected to a source of positive potential through a common resistance ill?. The cathodes 912 and 922, respectively, of the tubes 91 and 52 are connected to a source oi negative potential, such as, for example, a point at ground potential, through resistances 15 and 925, respectively, which are respectively shunted by capacitors 16 and 52e. The control voltage for the gate 71 is applied to the cathode 912 of the tube 91, and the control voltage for the gate 72 is applied to the cathode 22 of the tube 92.

The flip-dop circuit 9 is connected through an integrator circuit 9?; to the single-phase line 999 of the A.C.

output network. The single-phase line 98'() connects the cathodes 112, 122 and 132 of the ignitrons 11, 12 and 13, respectively, and the anodes 141, 151 and 161 of the ignitrons 14, 15 and 16, respectively, with each other. By means of the connection through the integrator circuit 93, the flip-flop circuit 9 is controlled in such a Way that the tube 92 is made conductive and the tube 91 is made nonconductive upon the occurrence of each positive half cycle of the single-phase current, since the positive half cycles ilow through the ignitrons 11, 12 and 13. The tube 91 is made conductive and the tube 92 is made non-conductive upon the occurrence of each negative half cycle `of the single-phase current, since the negative halt cycles flow through the ignitrons 11i, 15 and 16.

The control signal source t5 supplies via a second control signal supply line 82, a positive control voltage or control signal which is retained for the period of time during which the single-phase alternating current should flow. The control voltage in the second control signal supply line S2 controls the gates 61 and 62. The flip-flop circuit 9 and the gates 71 and 72 are included in the overcurrent control means which controls the energization of the ring counter circuit 5.

ln explaining the operation o the circuit arrangement of FlG. l, it is first assumed that the single-phase current is delivered by means or" a control signal delivered to the rst control signal supply line S1, so that the control signal source S orly provides a control voltage in the second control signal supply line 82. n the ring counter circuit 5, one oi the tubes 51, 52, 5S and 54 is ignited for `a period of time and is then extinguished while a second of said tubes is simultaneously ignited and remains ignited for a given period oi time. Then, the second tube is extinguished While the third of said tubes is simultaneously ignited tor a given period of time, and the fourth of said tubes is then ignited simultaneously with the extinguishing of the third tube. The ignition times of the tubes are determined by the time delay circuits 517, 52?, 537 and 547. While the tube 51 is ignited, its cathode 12 has a positive potential which is delivered to the input ot the gate 61. Under the intluence of the positive control voltage in the second control signal supply line .(32, the diode #i12 of the gate 61 is maintained polarized in its nonconductive direction so that said gate is open and the potential of the cathode 512 of the tube 51 reaches the ignition electrodes 413, 423 and 433 of the respective tubes d1, i2 and rtl-3 through the resistance 611 and through the respective one ot the resistances 41o, and 36. Thus, the ignition electrodes of the cold cathode tubes 41, 42 and d3 are initially charged with a positive potential as long as the tube 51 is ignited and as long as the control signal source S provides a control voltage in the second control signal supply line S2, whereby the said control voltage opens the gate 61. Each of the tubes 51, l2 and L33 is ignited as soon as it receives a pulse from the pulse source 415, 425 and 435, respectively. The lastmentioned pulse is necessary for the ignition control of said tubes through the respective capacitor 414-, 42d, and 434, and the said last-mentioned pulse ignites the said tubes if a square wave voltage from the square wave voltage source S143-, 82d and 834, respectively, is simultaneously provided in phase with the anode potential of the respective associated thyratron 31, 32 and 33. As soon as the anode current of one of the tubes d1, e2 and 43 is established, the respective one of the thyratrons 31, 52 and 33 is ignited. This produces a positive charge on the associated one of the ignition electrodes 113, 123 and 133 of the ignitrons 11, 12 and 13, respectively, associated with the respective thyratron so that said one of said ignitrons ignites. In this manner, the positive half cycle of the single-phase current is obtained in the transformer 2 from the three-phase lines R, S, T with the help of ignitrons 11, 12 and 13. Since the tubes 52, 53 and 54 of the ring counter circuit 5 are extinguished when the tube S1 is ignited, the cathode 532 of the tu e 53 does not have a positive potential so that the ignition electrodes 443, 453 and 463 of the cold cathode tubes 44, 45 and 46, respectively, are not initially charged with a positive potential and these tubes cannot ignite. Thus, the thyratrons 3d, 35 and 36 and the igt trons 14, 15 and 16 associated with the cold cathode tubes 44, 45 and i5 remain extinguished.

When the tube 51 of the ring counter 5 is extinguished (and the tube 52 ignites), the ignition electrodes 413, 423 and 433 of the tubes 41, 42 and 43, respectively, receive no further initial voltage. The tubes 41, 42 and 43 are then extinguished upon termination of the supply of square Wave voltage from the square wave voltage sources Sid, {i2-t and 834i, respectively. The thyratrons 31, 32 and 33 and the ignitrons 11, 12 and 13 are extinguished in the next sten, as soon as the phase voltage of their associate-d phase drops below the extinguishing voltage of said thyratrons and ignitrons. Thus, the iwitrons 11, 1.2 and 13 carry anode current even after the extinguishing of the tube 1 until the voltage or the phase with which they are associated drops to the extinguishing voltage of said ignitrons. When the tube 51 in the ring counter circuit 5 is extinguished, the tube S2 is ignited.

The tube 52 is extinguished after a period of time determined by the time delay circuit S27, whereupon the tube S3 is ignited and its cathode becomes positive. The cathode potential of the tube 53 is applied to the ignition electro-des ff/i3, 453, and f5.3 of the tubes 44, 45 and 46, respectively, because the gate o2 is open since the control voltage in the second control signal supply line S2 maintains the diode 622 polarized in its non-conductive direction. Thus, each of the cold rcathode tubes 44, 45 and 46 ignites as soon as it receives its pulse from the pulse sources 445, 45S and 1t/:5, respectively, and its square wave voltage from the square wave voltage sources S44, 354- and respectively. Consequently, the thyratrons 34, and 3o associated with the respective cold cathode tube d4, e5 and 46 and the ignitrons 1d, 15 and 16 associated with the respective thyratron is then ignited. The ignitrons 14, 15 and 16 conduct the negative half cycle of the single-phase current. After a period of time determined by the time delay circuit 537, the tube S3 is extinguished and the tube 54 is simultaneously ignited. When the tube 53l is extinguished, the initial potential on the ignition electrodes 4523, 53, and of the tubes 15A-t1, t5 and fr-6, respectively, disappears. Each of these tubes remains ignited only until the termination of the square wave voltage from the respective square wave voltage sources 31E-4, 351.1, and S d, and each of :the thyratrons 34's, 35 and 36 and each of the ignitrons 14, '15' and lo remains ignited only until :the phase potential drops below the extinguishing potential of the respective thyratron and ignitron. After a period of time which is determined by the time `delay circuit 547, the tube 54 of the ring counter 5 is extinguished and the tube 51 is simultaneously ignited, whereby the aforedescribed procedure is repeated in that a positive halt cycle of the singlephase current is obtained.

Since in each instant one or two of the lines R, S, T has `a positive potential lwith respect to the neutral point O and since two or one of these conductors has a negative 'potential with respect to the neutral point, the frequency of 'the single-phase alternating current for all practical purposes can be selected at will by means ot the time delay circuits S17, 527, 537 `and 547. ln Welding apparatus of the type utilizing the power supply circuit of the type described, the frequency of the single-phase current as a rule is selected to be lower than the frequency of the polyphase current.

Under the iniluence of each positive half cycle of the single-phase current, the tube 92 of the tlip-` rop circuit 9 lis conductive and the tube 91 is non-conductive at the same time While, under the iniiuence of each negative half cycle of the single-phase current, the tube 91 is conductive and lthe tube 92 is simultaneously non-conductive- When the tube 92 is conductive, its cathode 922 has a positive ateatro/i potential which maintains the diode 72d of the gate 72 polarized in its non-conductive direction so that said gat is open. Thus, the gate 72 is open during each .positive halt" cycle ofthe single-phase alternating current. Simultaneously, the gate '7l is closed, :because the diode ill does not receive from the cathode @Jgot the non-conductive tube ,91 a voltage suthcient to maintain said diode polarized in its non-conductive direction. The diode idl is thus polarized in its conductive direction and represents `a short circuit Ijor :a signal or pulse till which may Ibe provided by the dirs-t control signal supply line Si. Similarly, under the intluence of each negative half cycle of the sin glo-phase current, the gate 72 is closed and the gate 7i is open, lbecause the negative half cycle of the single-lhasa alternating circuit causes the tube 92 to become non-conductive and causes the tube fr to become conductive.

When the single-phase alternating current is to be discontinued (that is, when the power supply circuit is to be deenergized), the control voltage in the second control signal supply line 82 is interrupted. `As soon as the last-mentioned second control voltage is terminated, diodes 6l?, and 622 oi the gates oi and 62, respectively, no longer subjected to a voltage maintaining them polarized in their non-conductive direction so that said diodes are polarized in their conductive direction and gates are closed because the said diodes provide short circuits tor the positive cathode potential ot the tubes l `and 53, respectively. ln such instances, the ignition electrodes di e323, 433, i4/3, 453 and 453 or" the cold cathode tubes el, 4Z, e3, `Aid, d5 and do, respectively, do not receive an initial potential and therefore said tubes cannot be ignited under the influence of pulses from the pulse sources ii, 4125, @35, 44S, 455 and 4&5' and of the square wave voltages from the square wave voltage sources 811-, 251, 33e, 34d, 85d and hat one ot the cold cathode tubes dl, 42, d3, 44, d5 and to which is ignited at the time that the control potential from the control signal source 8 `iS terminated, is extinguished as soon as the square wave voltage applied to its anode circuit is terminated. Thus, none `ot the thyratrons 3l, 32, 33, 34, 35 `and 3o and none of the ignitrons ill, i2, i3, 1d, lo and i6 which are controlled by these thyratrons can be ignited and the momentarily ignited thyratron and ignitron are extinguished as soon as the voltage ot the phase associated with said thyratron and ignitron drops to the extinguishing voltage of the said thyratron and ign-itron. In this manner, the singlephase current is discontinued whereas the hip-flop circuit Q remains in a condition determined bythe polarity of the last half cycle of the single-phase alternating current. Aif the last half cycle of the single-phase alternating current was of positive polarity, the tube 92 was conductive while the tube 9i twas non-conductive and the gate '72 is open and the gate 71 is closed. However, if the last half cycle or" the single-phase alternating current was of negative polarity, the tube 91 was conductive and the tube 92 was non-conductive so that the gate 72 was closed and the gate '7l was open.

When the single-phase alternating current is to be provided (that is, `when the power supply circuit is to be energized), the control signal source 8 provides `a iirst control signal or pulse Sil in the tirst control signal supply line Si and said control signal source also provides a second control signal or pulse in vthe second control signal supply line E2. The con-trol signal source 3 continues to provide the tirst and second contr-ol signals for the period of energization of the power supply circuit.

if the last halt cycle of the single-phase alternating cur-rent was a positive half cycle, the tube 9i; of the flipflop circuit 9 is non-conductive and the tube 92 is conductive so that the gate '7i is closed and the gate i2 is open. The control signal or pulse @il vpasses through the open gate 72 and the amplifier 723 to the ignition electrode 53d of the tube 53. The tube 53 is then ignited. Simultaneously, the control voltage in the second control signal supply line S2 opens the gates 6i' and The cathode ot the tube :'33 then provides a positive initial voltage through the open gate 62 to the ignition electrodes i4-i3, 453 and 453 of the tubes ed, t5 and do, respectively. Each of the tubes Lid, and to is then ignited by the ulse from the associated pulse source 445, 455 and 65 by the square wave voltage from the associated square wave voltage source dell, 854 and respectively. in such manner, the iirst half cycle ot the singlephase current upon energization of the power supply circuit is of negative Ipolarity whereas the halt cycle at w Aich said power supply circuit was deenergized was positive and this prevents the generation of overcurrents in the transformer 2. The ring counter circuit 5 then switches over to the tube 5d, whereupon the cold cathode tubes de, i5 and 46, the thyratrons Z-fl, 35 and 35 and the ignitrons i4, t5 and 'lo then extinguish in the same manner as described for the cold cathode tubes di, and 43, the thyratrons 3i, 32 and 33, and the ignitrons il, i2 and i3, respectively. rThe ring counter circuit then switches over to the tube 5l. r'he tube 5i then again aids in providing a positive half cycle oi the singlephase current. Upon further switching of the ring counter 5 over to the tube 52 and then to the tube S3, a negative halt cycle of the single-phase current is provided, and so forth. This procedure is repeated as long as control voltage is provided by the second control signal supply line it the last halt cycle of the single-phase alternating current prior to the deenergization of the power supply circuit was a negative half cycle, the tube @i of the tiiptlop circuit 9 is conductive and the tube 92 is non-conductive after the single-phase current is discontinued. rEhe gate is then open and the gate 72 is closed. When the single-phase current is continued, the control signal or pulse ill-il passes. through the open gate 7i and the ai plier 713 to the ignition electrode 514 of the tube 5. The tube is then ignited and provides voltage through the open gate 6l for the ignition electrodes E-, 423 and 433 of thc respective cold cathode tubes di, i2 and The gate el is opened by the control voltage the second control signal supply line rl`he tubes 4l, 4Z and d3 then aid in providing a positive halt cycle of the single-phase current via the thyratrons Si, 32 and 33 and the ignitrons lli, l2 and i3 in the describe-.i manner.

Thus, when the single-phase current is continued (that is, when the power supply circuit is energized), said single-phase current always begins with a halt cycle whose polarity is opposite to the polarity of the halt cycle present when said single-phase current was discontinued (that is, when the power supply circuit was deenergized). ln this manner, the direction of magnetization ot the core 2? of the transformer 2 is reversed whenever the singlephase current is continued, so that the change in induction produces a strong countervoltage which prevents the generation of overcurrents at the time of energization of the power supply circuit.

The ring counter circuit 5 can continue its operation during the intervals in the single-phase current. it the length ot the interval between the times of continuation and discontinuation of the single-phase current does not equal a whole multiple of the duration period or" single-phase current, one of the tubes 52, 53 and 5d is ignited, it at the time of continuation th tube Si. is ignite l. @ne of the tubes 5l, 52 and 5d is ignited if, at the time of continuation of the single-phase current, thtube 53 is ignited. The ignition of the tube e* or 5' causes the ignited tube to be extinguished, tha system passes through the ring counter stages o previously ignited tube to the newly ignited tube Si o However, the ring counter circuit 5 can also be disconnected at the time that the single-phase current is connected or discontinued. ln such instance, the stepwise switching operation of the ring counter circuit Si begins With the ignited tube 51 or 53 when the singlephase current is continued.

The integrator circuit 93, through which the iiip-iiop cirucit 9 is controlled by the single-phase current, functions to prevent peak voltages from occurring at the time that the transformer 2 is energized or peak` voltages produced by certain phenomena at the secondary Winding 22 of said transformer. Such peak voltages could interfere with the control of the condition of the iiip-iiop circuit by the single-phase current.

Instead of the iiip-liop circuit 9 and the gates 71 and 72, a polarized relay may be utilized. FlG. 2 illustrates a portion of the circuit arrangement of FG. l modified by the provision of a polarized relay. Similar components in FIGS. l and 2 are identified by the same reference numerals.

ln FIG. 2, a resistance 24 is connected in series with the transformer 2., and the Winding 251 of polarized relay T is connected to a point common to said transformer' and said resistance. The polarized relay Z5 has a maliebreak Contact comprising an armature 252 and two contacts 253 and lfd-4:. rEhe armature 2@ is connected to the first control signal supply line iii. The Contact 7.53 is connected to the input of the amplifier '713 and the output of said amplifier is connected to the ignition electrode 514' ot the tube 5l of the ring counter circuit 5 (not shown in llG. 2). The Contact 254 is connected to the input of the amplifier 723 and the output of said amplifier is connected to the ignition electrode or" the tube 53 of the ring counter circuit 5 (not shown in FIG. 2). The excitation coil 253i of the polarized relay 25 is poled in such a way that the armature 252 moves into contact with the Contact 2.54 upon the occurrence of each positive half cycle of the single-phase current and said armature contacts the contact 253 upon the occurrence of. each negative half cycle of the single-phase current.

The operation of the circuit of liiG. 2 corresponds to the operation of the circuit of FIG. l except that the first control signal supply line Si is not connected to the second ignition electrodes 534 and 51d of the tubes 53 and 5l, respectively, through the respective gates 71 and '72 controlled by the f i -iiop circuit 9. instead, the first control signal supply line $1 is connected to the second ignition electrodes 534 and 5&4 by the armature 252, which armature connects said line with the second ignition electrode S34 of the tube 53 under the control of the excitation Winding 251 and each positive half cycle of the single-phase AC. current and With the second ignition electrode 514i of the tube 5l under the control of said excitation Winding and each negative half cycle of the single-phase A.C. current.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications Without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended Within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. A current control circuit arrangement comprising, in combination,

iirst phase converting means for converting a multiphase alternating current to a half cycle of positive polarity of single-phase alternating current and having an input, an output and an energization control;

second phase converting means for converting a multiphase alternating current to a half cycle of negative polarity of single-phase alternating current and having an input, tan output and an energization control;

means for supplying a multiphase alternating current to the inputs of said iirst and second phase convertin(y means;

transformer means connected to the outputs of said first and second phase converting means;

phase converting control means for alternately energizing said first and second phase converting means and having inputs and outputs connected to the energization controls of the said first and second phase converting means, said phase converting control means comprising a ring counter circuit including a first stage having input means and output means and a second stage connected diametrically opposite said first stage and having input means and output means, the input means or" said first and second stages constituting the inputs of said phase converting control means and the output means of t e said first and second stages constituting the outputs of the said phase converting control means; and

control means for controlling in accordance with said single-phase alternating current said phase converting control means to initially energize upon energization of said transformer means by one of said first and second phase converting means that one of the said iirst and second phase converting means producing a single-phase alternating current of opposite half cycle polarity from the last half cycle polarity of the single-phase alternating current produced upon the previous deenerglzation or" the said transformer means, said control means having an input connected to the outputs of the said iirst and second phase converting means and outputs connected to the inputs of said phase converting control means.

2. A current control circuit arrangement comprising,

in combination,

first phase converting means for converting a multiphase alternating current to a half cycle of positive polarity of single-phase alternating current and having an input, an output and an energization control;

second phase converting means for converting a multiphase alternating current to a halt cycle of negative polarity of single-phase alternating current and having an input, an output and an energization control;

means for supplyint7 a multiphase alternating current to the inputs of said first and second phase converting means;

transformer means connected to the outputs of said first and second phase converting means;

a ring counter circuit for alternately energizing said first and second phase converting means, said ring counter circuit including a first stage having input means and output means and a second stage connected diametrically opposite said first stage and having input means and output means, first coupling means coupling the output means of said first stage to the input means of said second stage and second coupling means coupling the output means of said second stage to the input means of said first stage, a first time delay circuit included in said first coupling means and a second time delay circuit included in said second coupling means, said first and second time delay means determining the frequency of said single phase alternating current provided by said iirst and second phase converting means, the output means of said rst stage being connected to the energization control of said first phase converting means and the output means of said second stage being connected to the energization control of said second phase converting means; and

control means comprising a control signal source providing a starting pulse for starting said single-phase current, a starting pulse supply line connected to said control signal source for supplying said starting pulse, bistable circuit means having an energization control `connected to the outputs or said first and second phase converting means and adapted to set said bistable circuit means in a first of two stable conditions when the alternating current half Wave delivered by said first and second phase converting means has a positive polarity and to set said bistable circuit means in a second of its two stable conditions when the alternating current half wave delivered by said first and second phase converting means has a negative polarity, and circuit means controlled by said energization control of said bistable circuit means in circuit with said starting pulse supply line and with the input means of the first and second stage of said ring counter `circuit and adapted to connect said starting pulse supply line to the input means of the first stage of said ring counter circuit when said bistable circuit means is in the second of its twoconditions and to connect said starting pulse supply line to the input means of the second stage of said ring counter circuit when said bistable circuit means is in the first of its t-.vo conditions.

3. A current control circuit arrangement, as claimed in claim 2, further compri lng a filter circuit having an input and an output, the input of said lter circuit being connected to the output of said first and second phase converting means and the output of said tilter circuit being connected to the energization control of said bistable circuit means, said tilt-er circuit being adapted to transmit the frequency of said single-phase current and to suppress frequencies dillerent from the frequency of said singlephase current.

4. A current control cir uit arrangement, as claimed in claim 2, further comprising a rst gate controlled means connected between the output of the lirst stage of said ring counter circuit and the energization control of said first phase converting means and second gate controlled means connected between the output of the second stage of said ring counter circuit and the energizatiori control of said second phase converting means, the control signal source of said control means comprising means for supplying a control voltage which is retained for the period of time during which the single-phase alternating current should flow, and a control voltage supply line connected to the control signal source of said control means and to the first and second gate means of said ring counter circuit, the first gate means of said ring counter circuit being conductive between the output of the first stage of said ring counter circuit and the energization control of said first phase converting means and the second gate means of said ring counter circuit being conductive between the output of the second stage of said ring counter circuit and the energization means of said second phase converting means in response to said control voltage. u

5. A current control circuit arrangement comprising, in combination,

rst phase converting means for converting a multipliase alternating current to a halt cycle of poslive polarity of single-phase alternating current and having an input, an output and an energization control;

second phase converting means for converting a multiphase alternating current to a naif cycle of negative polarity of single-phase alternating current and having an input, an output and an energization control;

means for supplying a multiphase alternating current to the inputs of said first and second phase converting means;

transformer means connected to the outputs of said first and second phase converting means;

a ring counter circuit for alternately energizing said first and second phase converting means and including a first electron discharge stage having rst and second ignition electrodes, an lanode and a cathode, a second electron discharge stage having first and second ignition electrodes, anode and a cathode, first and second time delay circuits, first coupling means including said first time delay circuit coupling the cathode of said first stage to the first ignition electrode of said second stage, and second coupling means including said second time delay circuit coupling the cathode of said second stage to the first ignition electrode of said iirst stage, the cathode of said first stage being connected to the energization control of said first phase converting means and the cathode of said second stage being connected to the energization control of said second phase converting means; and

control means comprising a control signal source providing a starting pulse for starting said single-phase current, a starting pulse supply line connected to said control signal source for supplying said starting pulse, a bistable multivibrator circuit having input means connecte to the outputs of said first and second phase converting means and adapted to set said multivibrator circuit in 4a first of two stable conditions when the alternating current half wave delivered by the outputs of said lirst and second phase converting means has a positive polarity and to set said multivibrator circuit in a second of its two stable conditions when the alternating current half Wave delivered by the outputs of said first and second phase converting means has a negative polarity, output means included in said multivibrator circuit, first gate means connected between said starting pulse supply line and the second ignition electrode of the first stage of said ring counter circuit, rst gate control means associated with said first gate means and connected to the output means of said multivibrator circuit and adapted to render said first gate means conducting when said multivibrator circuit is in said second of its two stable conditions, second gate means connected between said starting pulse supply line and the second ignition electrode of the second stage of said ring counter circuit, and second gate control means associated with said second gate means and connected to the output means of said multivibrator circuit and adapted to render said second gate means conducting when said multivibrator circuit is in said rst of its two stable conditions.

6. A current control circuit arrangement comprising,

in combination,

first phase converting means for converting a multiphase alternating current to a half cycle of positive polarity of single-phase alternating current and liaving an input, an output and an energization control;

second phase converting means for converting a multiphase alternating current to a half cycle of negative polarity of single-phase alternating current and having an input, an output and `an energization control;

means for supplying a multipliase alternating current to the inputs of said first and second phase converting means;

transformer means connected to the outputs of first and second phase converting means;

a ring counter circuit for alternately energizing said first and second phase converting means and including a first electron discharge stage having first and second ignition electrodes, an anode and a cathode, a second electron discharge stage having rst and second ignition electrodes, an anode and a cathode, first and second time delay circuits, rst coupling means including said first time delay circuit coupling the cathode of said first stage to the first ignition electrode of said second stage, and second coupling means including said second time delay circuit coupling the cathode of the second stage to the first ignition electrode of said first stage, the cathode of said first stage being connected to the energization control of said first phase converting means and the cathode of second stage being connected to the energization control of said second phase converting means; and

control means comprising a control signal source prosaid vidng a starting pulse fer starting said single-phase current, a starting pulse supply line connected to said control signal sour-:e for supplying said starting signal pulse, polarized relay means having an excitation Winding connected to the outputs of said first and second phase converting means, and double throw switching means in circuit with said starting pulse supply line and the second ignition electrode of the rst and second stages of said ring counter circuit, said double throw switching means connecting said starting pulse supply lline with the second ignition electrode of the first stage of said ring counter circuit when the alternating current half Wave delivered by said rst and second phase converting CII starting pulse supply line with the second ignition electrode of the second stage of said ring counter circuit when the alternating current half Wave delivered by said first and second phase converting means has a positive polarity.

References Cited by the Examiner UNTED STATES ?ATENTS 2,666,888 1/54 Riley et a1. 32a- 5s 10 2,676,297 4/54 Hills 666.1 323-442; 2,776,399 1/57 Sommeria 323-58 X LLOYD MCCGLLUM, Primary Examiner.

means has a negative polarity and connecting said 15 ORE L- RADER Examine"- 

1. A CURRENT CONTROL CIRCUIT ARRANGEMENT COMPRISING, IN COMBINATION, FIRST PHASE CONVERTING MEANS FOR CONVERTING A MULTIPHASE ALTERNATING CURRENT TO A HALF CYCLE OF POSITIVE POLARITY OF SINGLE-PHASE ALTERNATING CURRENT AND HAVING AN INPUT, AN OUTPUT AND AN ENERGIZATION CONTROL; SECOND PHASE CONVERTING MEANS FOR CONVERTING A MULTIPHASE ALTERNATING CURRENT TO A HALF CYCLE OF NEGATIVE POLARITY OF SINGLE-BASE ALTERNATING CURRENT AND HAVING AN INPUT, AN OUTPUT AND AN ENERGIZATION CONTROL; MEANS FOR SUPPLYING A MULTIPHASE ALTERNATING CURRENT TO THE INPUTS OF SAID FIRST AND SECOND PHASE CONVERTING MEANS; TRANSFORMER MEANS CONNECTED TO THE OUTPUTS OF SAID FIRST AND SECOND PHASE CONVERTING MEANS; PHASE CONVERTING CONTROL MEANS FOR ALTERNATELY ENERGIZING SAID FIRST AND SECOND PHASE CONVERTING MEANS AND HAVING INPUTS AND OUTPUTS CONNECTED TO THE ENERGIZATION CONTROLS OF THE SAID FIRST AND SECOND PHASE CONVERTING MEANS, SAID PHASE CONVERTING CONTROL MEANS COMPRISING A RING COUNTER CIRCUIT INCLUDING A FIRST STAGE HAVING INPUT MEANS AND OUTPUT MEANS AND A SECOND STAGE CONNECTED DIAMETRICALLY OPPOSITE SAID FIRST STAGE AND HAVING INPUT MEANS AND OUTPUT MEANS, THE INPUT MEANS OF SAID FIRST AND SECOND STAGES CONSTITUTING THE INPUTS OF SAID PHASE CONVERTING CONTROL MEANS AND THE OUTPUT MEANS OF THE SAID FIRST AND SECOND STAGES CONSTITUTING THE OUTPUTS OF THE SAID PHASE CONVERTING CONTROL MEANS; AND CONTROL MEANS FOR CONTROLING IN ACCORDANCE WITH SAID SINGLE-PHASE ALTERNATING CURRENT SAID PHASE CONVERTING CONTROL MEANS TO INITIALLY ENERGIZE UPON ENERGIZATION OF SAID TRANSFORMER MEANS BY ONE OF SAID FIRST AND SECOND PHASE CONVERTING MEANS THAT ONE OF THE SAID FIRST AND SECOND CONVERTING MEANS PRODUCING A SINGLE-PHASE ALTERNATING CURRENT OF OPPOSITE HALF CYCLE POLARITY FROM THE LAST HALF CYCLE POLARITY OF THE SINGLE-PHASE ALTERNATING CURRENT PRODUCED UPON THE PREVIOUS DEENERGIZATION OF THE SAID TRANSFORMER MEANS, SAID CONTROL MEANS HAVING AN INPUT CONNECTED TO THE OUTPUTS OF THE SAID FIRST AND SECOND PHASE CONVERTING MEAN AND OUTPUTS CONNECTED TO THE INPUTS OF SAID PHASE CONVERTING CONTROL MEANS. 